Can not find when was ArcGIS API for JavaScript first released?? I need a year of first release of the API.
Although there was Esri JavaScript before the Esri JavaScript API, it looks like the official JavaScript API came out in 2008. Here is a post on version 1.2: Version 1.2 of the ArcGIS JavaScript API released | ArcGIS Blog The Esri JS API used Dojo and here is a list of the versions of Dojo: Guide | ArcGIS API for JavaScript
Since Esri's standard practice is updating quarterly, 1.2 looks like the third update of 2008.
And according to this, it was June 2008: http://downloads.esri.com/support/product%20life%20cycle/online_gis/ArcGISWebMappingAPIs_PLC.pdf